Whistler

You're walking alone on the street at night, but then you hear another set of footsteps and a haunting tune being whistled by an unseen stranger. Fritz Lang used an similar premise in his 1930s German movie with Peter Lorre playing M, a psychopathic murderer of children. But the American radio series was even creepier. The unseen Whistler didn't kill anyone (that we know of), but he certainly loved watching murders take place, narrating them for us, and chuckling at the suffering of others instead of doing anything to stop it. Unlike M, he was never caught. He kept walking the streets every week for thirteen long years, whistling his ominous thirteen notes and telling us another tale of bizarre fate. Perhaps Fate is who the Whistler really was? He never provided any sir name, and the killer was usually punished by some twist of fate that only The Whistler seemed to expect.